U.S. patent application number 12/365999 was filed with the patent office on 2009-06-11 for electrically conductive elastic composite yarn, methods for making the same, and articles incorporating the same.
This patent application is currently assigned to Textronics Inc.. Invention is credited to Omero Consoli, George W. Coulston, Eleni Karayianni, Klaus J. Regenstein.
Application Number | 20090145533 12/365999 |
Document ID | / |
Family ID | 33418254 |
Filed Date | 2009-06-11 |
United States Patent
Application |
20090145533 |
Kind Code |
A1 |
Karayianni; Eleni ; et
al. |
June 11, 2009 |
ELECTRICALLY CONDUCTIVE ELASTIC COMPOSITE YARN, METHODS FOR MAKING
THE SAME, AND ARTICLES INCORPORATING THE SAME
Abstract
An electrically conductive elastic composite yarn comprises an
elastic member that is surrounded by at least one conductive
covering filament(s). The elastic member has a predetermined
relaxed unit length L and a predetermined drafted length of
(N.times.L), where N is a number preferably in the range from about
1.0 to about 8.0. The conductive covering filament has a length
that is greater than the drafted length of the elastic member such
that substantially all of an elongating stress imposed on the
composite yarn is carried by the elastic member. The elastic
composite yarn may further include an optional stress-bearing
member surrounding the elastic member and the conductive covering
filament. The length of the stress-bearing member is less than the
length of the conductive covering filament and greater than, or
equal to, the drafted length (N.times.L) of the elastic member,
such that a portion of the elongating stress imposed on the
composite yarn is carried by the stress-bearing member.
Inventors: |
Karayianni; Eleni; (Geneva,
CH) ; Consoli; Omero; (Geneva, CH) ; Coulston;
George W.; (Pittsburgh, PA) ; Regenstein; Klaus
J.; (Buedingen, DE) |
Correspondence
Address: |
CONNOLLY BOVE LODGE & HUTZ, LLP
P O BOX 2207
WILMINGTON
DE
19899
US
|
Assignee: |
Textronics Inc.
|
Family ID: |
33418254 |
Appl. No.: |
12/365999 |
Filed: |
February 5, 2009 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11553206 |
Oct 26, 2006 |
7504127 |
|
|
12365999 |
|
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|
|
10825498 |
Apr 15, 2004 |
7135227 |
|
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11553206 |
|
|
|
|
60465571 |
Apr 25, 2003 |
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Current U.S.
Class: |
156/47 |
Current CPC
Class: |
Y10T 428/2922 20150115;
Y10T 442/601 20150401; Y10T 442/3065 20150401; Y10T 442/655
20150401; Y10T 428/2925 20150115; Y10T 442/608 20150401; D02G 3/328
20130101; Y10T 442/3146 20150401; Y10T 442/696 20150401; Y10T
442/3008 20150401; Y10T 428/2936 20150115; Y10T 442/602 20150401;
Y10T 428/294 20150115; Y10T 428/2924 20150115; D02G 3/441 20130101;
Y10T 442/3976 20150401; Y10T 442/313 20150401 |
Class at
Publication: |
156/47 |
International
Class: |
H01B 13/00 20060101
H01B013/00 |
Claims
1. A method for forming an electrically conductive elastic
composite yarn comprising: an elastic member having a relaxed
length (L); and at least one conductive covering filament
surrounding the elastic member, the method comprising the steps of:
drafting the elastic member to a drafted length N.times.L where N
is from about 1.2 to about 8.0; placing a conductive covering
filament substantially parallel to and in contact with the drafted
length of the elastic member; and thereafter allowing the elastic
member to relax thereby to entangle the elastic member and the
conductive covering filament.
2. The method of claim 1 wherein the electrically conductive
elastic composite yarn further comprises a second conductive
covering filament surrounding the elastic member, the method
further comprising the steps of: placing a second conductive
covering filament substantially parallel to and in contact with the
drafted length of the elastic member; and thereafter allowing the
elastic member to relax thereby to entangle the second conductive
covering filament with the elastic member and the first conductive
covering filament.
3. The method of claim 2 wherein the electrically conductive
elastic composite yarn further comprises a stress bearing member of
an inelastic synthetic polymer yarn surrounding the elastic member,
the method further comprising the steps of: placing the stress
bearing member substantially parallel to and in contact with the
drafted length of the elastic member; and thereafter allowing the
elastic member to relax thereby to entangle the stress bearing
member with the elastic member and the first conductive covering
filament.
4. The method of claim 3 wherein the electrically conductive
elastic composite yarn further comprises a second inelastic
synthetic polymer yarn surrounding the elastic member, the method
further comprising the steps of: placing a second inelastic
synthetic polymer yarn substantially parallel to and in contact
with the drafted length of the elastic member; and thereafter
allowing the elastic member to relax thereby to entangle the second
inelastic synthetic polymer yarn with the elastic member, the
conductive covering filament and the stress bearing member.
5. The method of claim 1, wherein the elastic member comprises a
synthetic bicomponent multifilament textile yarn.
6. The method of claim 1, wherein the stress-bearing member is a
bicomponent yarn or a multifilament yarn blend.
7. A method for forming an electrically conductive elastic
composite yarn comprising: an elastic member having a relaxed
length (L); and at least one conductive covering filament
surrounding the elastic member, the method comprising the steps of:
drafting the elastic member to a drafted length N.times.L where N
is from about 1.2 to about 8.0; twisting the conductive covering
filament with the drafted elastic member; and thereafter allowing
the elastic member to relax.
8. The method of claim 7 wherein the electrically conductive
elastic composite yarn further comprises a second conductive
covering filament surrounding the elastic member, the method
further comprising the steps of: twisting the second conductive
covering filament with the drafted elastic member and the first
conductive covering filament; and thereafter allowing the elastic
member to relax.
8. The method of claim 8 wherein the electrically conductive
elastic composite yarn further comprises an inelastic synthetic
polymer yarn surrounding the elastic member, the method further
comprising the steps of: twisting the inelastic synthetic polymer
yarn with the elastic member and the conductive covering filament;
and thereafter allowing the elastic member to relax.
10. The method of claim 9 wherein the electrically conductive
elastic composite yarn further comprises a second inelastic
synthetic polymer yarn surrounding the elastic member, the method
further comprising the steps of: twisting the second inelastic
synthetic polymer yarn with the elastic member, the conductive
covering filament and the first inelastic synthetic polymer yarn;
and thereafter allowing the elastic member to relax.
11. The method of claim 7, wherein the elastic member comprises a
synthetic bicomponent multifilament textile yarn.
12. The method of claim 7, wherein the stress-bearing member is a
bicomponent yarn or a multifilament yarn blend.
13. A method for forming an electrically conductive elastic
composite yarn comprising, an elastic member having a relaxed
length (L); and at least one conductive covering filament
surrounding the elastic member, the method comprising the steps of:
forwarding the elastic member through an air jet with the elastic
member stretched to a length N.times.L where N is from about 1.2 to
about 8.0; within the air jet, covering the elastic member with the
conductive covering filament; and thereafter allowing the elastic
member to relax.
14. The method of claim 13 wherein the electrically conductive
elastic composite yarn comprises a second conductive covering
filament surrounding the elastic member, the method further
comprising the steps of: within the air jet, covering the elastic
member and the first conductive covering filament with a second
conductive covering filament; and thereafter allowing the elastic
member to relax.
15. The method of claim 13 wherein the electrically conductive
elastic composite yarn further comprises an inelastic synthetic
polymer yarn surrounding the elastic member, the method further
comprising the steps of: within the air jet, covering the elastic
member and the conductive covering filament with an inelastic
synthetic polymer yarn; and thereafter allowing the elastic member
to relax.
16. The method of claim 15 wherein the electrically conducive
elastic composite yarn further comprises a second inelastic
synthetic polymer yarn surrounding the elastic member, the method
further comprising the steps of: within the air jet, covering the
elastic member, the conductive covering filament and the first
inelastic synthetic polymer yarn with a second inelastic synthetic
polymer yarn; and thereafter allowing the elastic member to
relax.
17. The method of claim 13, wherein the elastic member comprises a
synthetic bicomponent multifilament textile yarn.
18. The method of claim 13, wherein the stress-bearing member is a
bicomponent yarn or a multifilament yarn blend.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a divisional of U.S. application Ser.
No. 11/553,206, filed Oct. 26, 2006, currently pending, which was a
divisional of U.S. application Ser. No. 10/825,498, filed Apr. 15,
2004, issued as U.S. Pat. No. 7,135,227 on Nov. 14, 2006, which
claims the benefit of U.S. Provisional Application No. 60/465,571,
filed on Apr. 25, 2003, which provisional application is
incorporated in its entirety as a part hereof for all purposes.
FIELD OF THE INVENTION
[0002] The present invention relates to elastified yarns containing
conductive metallic filaments, a process for producing the same,
and to stretch fabrics, garments and other articles incorporating
such yarns.
BACKGROUND OF THE INVENTION
[0003] It is known to include in textile yarns metallic wires and
to include metallic surface coatings on yarns for the purpose of
carrying electrical current, performing an anti-static electricity
function or to provide shielding from electric fields. Such
electrically conductive composite yarns have been fabricated into
fabrics, garments and apparel articles.
[0004] It is believed impractical to base a conductive textile yarn
solely on metallic filaments or on a combination yarn where the
metallic filaments are required to be a stressed member of the
yarn. This is due to the fragility and especially poor elasticity
of the fine metal wires heretofore used in electrically conducting
textile yarns.
[0005] Sources of fine metal wire fibers for use in textiles
include, but are not limited to; NV Bekaert SA, Kortrijk, Belgium;
Elektro-Feindraht AG, Escholzmatt, Switzerland and New England Wire
Technologies Corporation, Lisbon, N.H. As illustrated in FIG. 1a
such wires 10 have an outer coating 20 of an insulating polymeric
material surrounding a conductor 30 having a diameter on the order
of 0.02 mm-0.35 mm and an electrical resistivity in the range of 1
to 2 microohm-cm. In general, these metal fibers exhibit a low
force to break and relativity little elongation. As shown in FIG. 2
these metal filaments have a breaking strength in the range of 260
to 320 N/mm.sup.2 and an elongation at break of about 10 to 20%.
However, these wires exhibit substantially no elastic recovery. In
contrast, many elastic synthetic polymer based textile yarns
stretch to at least 125% of their unstressed specimen length and
recover more than 50% of this elongation upon relaxation of the
stress.
[0006] U.S. Pat. No. 3,288,175 (Valko) discloses an electrically
conductive elastic composite yarn containing nonmetallic and
metallic fibers. The nonmetallic fibers used in this composite
conducting yarn are textile fibers such as nylon, polyester,
cotton, wool, acrylic and polyolefins. These textile fibers have no
inherent elasticity and impart no "stretch and recovery" power.
Although the composite yarn of this reference is an electrically
conductive yarn, textile material made therefrom fail to provide
textile materials having a stretch potential.
[0007] Similarly, U.S. Pat. No. 5,288,544 (Mallen et al.) discloses
an electrically conductive fabric comprising a minor amount of
conductive fiber. This reference discloses conductive fibers
including stainless steel, copper, platinum, gold, silver and
carbon fibers comprising from 0.5% to 2% by weight. This patent
discloses, by way of example, a woven fabric towel comprising
polyester continuous filaments wrapped with carbon fibers and a
spun polyester (staple fiber) and steel fiber yarn where the steel
fiber is 1% by weight of the yarn. While fabrics made from such
yarns may have satisfactory anti-static properties apparently
satisfactory for towels, sheets, hospital gowns and the like; they
do not appear to possess an inherent elastic stretch and recovery
property.
[0008] United States Patent Application 2002/0189839A1, published
19 Dec. 2002, (Wagner et al.), discloses a cable to provide
electrical current suitable for incorporation into apparel,
clothing accessories, soft furnishings, upholstered items and the
like. This application discloses electric current or signal
carrying conductors in fabric-based articles based on standard flat
textile structures of woven and knitted construction. An electrical
cable disclosed in this application includes a "spun structure"
comprising at least one electrically conductive element and at
least one electrically insulating element. No embodiments appear to
provide elastic stretch and recovery properties. For applications
of the type contemplated the inability of the cable to stretch and
recover from stretch is a severe limitation which limits the types
of apparel applications to which this type of cable is suited.
[0009] Stretch and recovery is an especially desirable property of
a yarn, fabric or garment which is also able to conduct electrical
current, perform in antistatic electricity applications or provide
electric field shielding. The stretch and recovery property, or
"elasticity", is ability of a yarn or fabric to elongate in the
direction of a biasing force (in the direction of an applied
elongating stress) and return substantially to its original length
and shape, substantially without permanent deformation, when the
applied elongating stress is relaxed. In the textile arts it is
common to express the applied stress on a textile specimen (e.g. a
yarn or filament) in terms of a force per unit of cross section
area of the specimen or force per unit linear density of the
unstretched specimen. The resulting strain (elongation) of the
specimen is expressed in terms of a fraction or percentage of the
original specimen length. A graphical representation of stress
versus strain is the stress-strain curve, well-known in the textile
arts.
[0010] The degree to which fiber, yarn or fabric returns to the
original specimen length prior to being deformed by an applied
stress is called "elastic recovery". In stretch and recovery
testing of textile materials it is also important to note the
elastic limit of the test specimen. The elastic limit is the stress
load above which the specimen shows permanent deformation. The
available elongation range of an elastic filament is that range of
extension throughout which there is no permanent deformation. The
elastic limit of a yarn is reached when the original test specimen
length is exceeded after the deformation inducing stress is
removed. Typically, individual filaments and multifilament yarns
elongate (strain) in the direction of the applied stress. This
elongation is measured at a specified load or stress. In addition,
it is useful to note the elongation at break of the filament or
yarn specimen. This breaking elongation is that fraction of the
original specimen length to which the specimen is strained by an
applied stress which ruptures the last component of the specimen
filament or multifilament yarn. Generally, the drafted length is
given in terms of a draft ratio equal to the number of times a yarn
is stretched from its relaxed unit length.
[0011] Elastic fabrics having conductive wiring affixed to the
fabric for use in garments intended for monitoring of physiological
functions in the body are disclosed in U.S. Pat. No. 6,341,504
(Istook). This patent discloses an elongated band of elastic
material stretchable in the longitudinal direction and having at
least one conductive wire incorporated into or onto the elastic
fabric band. The conductive wiring in the elastic fabric band is
formed in a prescribed curved configuration, e.g., a sinusoidal
configuration. The elastic conductive band of this patent is able
to stretch and alter the curvature of the conduction is wire. As a
result the electrical inductance of the wire is changed. This
property change is used to determine changes in physiological
functions of the wearer of a garment including such a conductive
elastic band. The elastic band is formed in part using an elastic
material, preferably spandex. Filaments of the spandex material
sold by DuPont Textiles and Interiors, Inc., Wilmington, Del.,
under the trademark LYCRA.RTM. are disclosed as being a desirable
elastic material. Conventional textile means to form the conductive
elastic band are disclosed, these include warp knitting, weft
knitting, weaving, braiding, or non-woven construction. Other
textile filaments in addition to metallic filaments and spandex
filaments are included in the conductive elastic band, these other
filaments including nylon and polyester.
[0012] While elastic conductive fabrics with stretch and recovery
properties dominated by the spandex component of the composite
fabric band are disclosed, these conductive fabric bands are
intended to be discrete elements of a fabric construction or
garment used for prescribed physiological function monitoring.
Although such elastic conductive bands may have advanced the art in
physiological function monitoring they have not shown to be
satisfactory for use in a way other than as discrete elements of a
garment or fabric construction.
[0013] In view of the foregoing it is believed desirable to provide
a conductive textile yarn with elastic recovery properties which
can be processed using traditional textile means to produce
knitted, woven or nonwoven fabrics, Further, it is believed that
there is yet a need for fabrics and garments which are
substantially wholly constructed from such elastic conductive
yarns. Fabrics and garments substantially wholly constructed from
elastic conductive yarns provide stretch and recovery
characteristic to the entire construction, conforming to any shape,
any shaped body, or requirement for elasticity.
SUMMARY OF THE INVENTION
[0014] The present invention is directed to an electrically
conducting elastic composite yarn that comprises an elastic member
having a relaxed unit length L and a drafted length of (N.times.L).
The elastic member itself comprises one or more filaments with
elastic stretch and recovery properties. The elastic member is
surrounded by at least one, but preferably a plurality of two or
more, conductive covering filament(s). Each conductive covering
filament has a length that is greater than the drafted length of
the elastic member such that substantially all of an elongating
stress imposed on the composite yarn is carried by the elastic
member. The value of the number N is in the range of about 1.0 to
about 8.0; and, more preferably, in the range of about 1.2 to about
5.0.
[0015] Each of the conductive covering filament(s) may take any of
a variety of forms. The conductive covering filament may be in the
form of a metallic wire, including a metallic wire having an
insulating coating thereon. Alternatively the conductive covering
filament may take the form of a non-conductive inelastic synthetic
polymer yarn having a metallic wire thereon. Any combination of the
various forms may be used together in a composite yarn having a
plurality of conductive covering filament(s).
[0016] Each conductive covering filament is wrapped in turns about
the elastic member such that for each relaxed (stress free) unit
length (L) of the elastic member there is at least one (1) to about
10,000 turns of the conductive covering filament. Alternatively,
the conductive covering filament may be sinuously disposed about
the elastic member such that for each relaxed unit length (L) of
the elastic member there is at least one period of sinuous covering
by the conductive covering filament.
[0017] The composite yarn may further comprise one or more
inelastic synthetic polymer yarn(s) surrounding the elastic member.
Each inelastic synthetic polymer filament yarn has a total length
less than the length of the conductive covering filament, such that
a portion of the elongating stress imposed on the composite yarn is
carried by the inelastic synthetic polymer yarn(s). Preferably, the
total length of each inelastic synthetic polymer filament yarn is
greater than or equal to the drafted length (N.times.L) of the
elastic member.
[0018] One or more of the inelastic synthetic polymer yarn(s) may
be wrapped about the elastic member (and the conductive covering
filament) such that for each relaxed (stress free) unit length (L)
of the elastic member there is at least one (1) to about 10,000
turns of inelastic synthetic polymer yarn. Alternatively, the
inelastic synthetic polymer yarn(s) may be sinuously disposed about
the elastic member such that for each relaxed unit length (L) of
the elastic member there is at least one period of sinuous covering
by the inelastic synthetic polymer yarn.
[0019] The composite yarn of the present invention has an available
elongation range from about 10% to about 800%, which is greater
than the break elongation of the conductive covering filament and
less than the elastic limit of the elastic member, and a breaking
strength greater than the breaking strength of the conductive
covering filament.
[0020] The present invention is also directed to various methods
for forming an electrically conductive elastic composite yarn.
[0021] A first method includes the steps of drafting the elastic
member used within the composite yarn to its drafted length,
placing each of the one or more conductive covering filament(s)
substantially parallel to and in contact with the drafted length of
the elastic member; and thereafter allowing the elastic member to
relax thereby to entangle the elastic member and the conductive
covering filament(s). If the electrically conducting elastic
composite yarn includes one or more inelastic synthetic polymer
yarn(s) such inelastic synthetic polymer yarn(s) are placed
substantially parallel to and in contact with the drafted length of
the elastic member; and thereafter the elastic member is allowed to
relax thereby to entangle the inelastic synthetic polymer yarn(s)
with the elastic member and the conductive covering
filament(s).
[0022] In accordance with other alternative methods, each of the
conductive covering filament(s) and each of the inelastic synthetic
polymer yarn(s) (if the same are provided) are either twisted about
the drafted elastic member or, in accordance with another
embodiment of the method, wrapped about the drafted elastic member.
Thereafter, in each instance, the elastic member is allowed to
relax.
[0023] Yet another alternative method for forming an electrically
conducting elastic composite yarn in accordance with the present
invention includes the steps of forwarding the elastic member
through an air jet and, while within the air jet, covering the
elastic member with each of the conductive covering filament(s) and
each of the inelastic synthetic polymer yarn(s) (if the same are
provided). Thereafter the elastic member is allowed to relax.
[0024] It also lies within the contemplation of the present
invention to provide a knit, woven or nonwoven fabric substantially
wholly constructed from electrically conducting elastic composite
yarns of the present invention. Such fabrics may be used to form a
wearable garment or other fabric articles substantially.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The invention will be more fully understood from the
following detailed description, taken in connection with the
accompanying drawings, which form a part of this application and in
which:
[0026] FIG. 1a is a scanning electron micrograph (SEM)
representation of a Prior Art electrically conducting metallic wire
with a polymeric electrically insulating outer coating, while FIG.
1b is a scanning electron micrograph (SEM) representation of the
electrically conducting wire of FIG. 1a after stress-induced
elongation to break;
[0027] FIG. 2 is a stress-strain curve for three electrically
conducting wires of the Prior Art wherein each electrically
conductive wire has a different diameter;
[0028] FIG. 3a is a scanning electron micrograph (SEM)
representation of an electrically conducting elastic composite yarn
in accordance with Invention Example 1 in a relaxed condition,
while FIG. 3b is a scanning electron micrograph (SEM)
representation of the electrically conducting elastic composite
yarn of FIG. 3a in a stretched condition;
[0029] FIG. 3c is a scanning electron micrograph (SEM)
representation of an electrically conducting elastic composite yarn
in accordance with Invention Example 2 of the present invention in
a relaxed condition, while FIG. 3d is a scanning electron
micrograph (SEM) representation of the electrically conducting
elastic composite yarn of FIG. 3c in a stretched condition;
[0030] FIG. 4 is a stress-strain curve for the electrically
conducting elastic composite yarn of Invention Example 1 determined
using Test Method 1, while
[0031] FIG. 5 is a stress-strain curve for the electrically
conducting elastic composite yarn of Invention Example 1 determined
using Test Method 2, and, in both FIGS. 4 and 5, for comparison,
the stress-strain curve of metal wire alone;
[0032] FIG. 6 is a stress-strain curve for the electrically
conducting elastic composite yarn of Invention Example 2 of the
invention determined using Test Method 1, and, for comparison, the
stress-strain curve of metal wire alone;
[0033] FIG. 7a is a scanning electron micrograph (SEM)
representation of an electrically conducting elastic composite yarn
(70) in accordance with Invention Example 3 in a relaxed condition,
while FIG. 7b is a scanning electron micrograph (SEM)
representation of the electrically conducting elastic composite
yarn of FIG. 7a in a stretched condition;
[0034] FIG. 7c is a scanning electron micrograph (SEM)
representation of an electrically conducting elastic composite yarn
in accordance with Invention Example 4 in a relaxed condition,
while FIG. 7d is a scanning electron micrograph (SEM)
representation of the electrically conducting elastic composite
yarn of FIG. 7c in a stretched condition;
[0035] FIG. 8 is a stress-strain curve for the electrically
conducting composite yarn of Invention Example 3 determined using
Test Method 1, and, for comparison, the stress-strain curve of
metal wire alone;
[0036] FIG. 9 is a stress-strain curve for the electrically
conducting composite yarn of Invention Example 4 determined using
Test Method 1, and, for comparison, the stress-strain curve of
metal wire alone;
[0037] FIG. 10a is a scanning electron micrograph (SEM)
representation of an electrically conducting elastic composite yarn
(90) in accordance with Invention Example 5 in a relaxed condition,
while FIG. 10b is a scanning electron micrograph (SEM)
representation of the yarn (90) of FIG. 10a in a stretched
condition;
[0038] FIG. 11 is a stress-strain curve for the electrically
conducting composite is yarn of Example 5 determined using Test
Method 1, and, for comparison, the stress-strain curve of metal
wire alone;
[0039] FIG. 12a is a scanning electron micrograph (SEM)
representation of a fabric made from the electrically conducting
elastic composite yarn in accordance with Invention Example 6, the
fabric being in a relaxed condition, while FIG. 12b is a scanning
electron micrograph (SEM) representation of a fabric from the same
composite yarn, the fabric being in a stretched condition;
[0040] FIG. 13a is a scanning electron micrograph (SEM)
representation of a fabric from the electrically conducting elastic
composite yarn of Invention Example 7, the fabric being in a
relaxed condition, while FIG. 13b is a scanning electron micrograph
(SEM) representation of same fabric in a stretched condition;
[0041] FIG. 14 is a schematic representation of an elastic member
sinuously wrapped with a conductive filament.
DETAILED DESCRIPTION OF THE INVENTION
[0042] In accordance with the present invention it has been found
that it is possible to produce an electrically conductive elastic
composite yarn containing metal wires, whether or not the wires are
insulated with polymeric coatings. The electrically conducting
elastic composite yarn according to the present invention comprises
an elastic member (or "elastic core") that is surrounded by at
least one conductive covering filament(s). The elastic member has a
predetermined relaxed unit length L and a predetermined drafted
length of (N.times.L), where N is a number, preferably in the range
from about 1.0 to about 8.0, representing the draft applied to the
elastic member.
[0043] The conductive covering filament has a length that is
greater than the drafted length of the elastic member such that
substantially all of an elongating stress imposed on the composite
yarn is carried by the elastic member.
[0044] The elastic composite yarn may further include an optional
stress-bearing member surrounding the elastic member and the
conductive covering filament. The stress-bearing member is
preferably formed from one or more inelastic synthetic polymer
yarn(s). The length of the stress-bearing member(s) is less than
the length of the conductive covering filament such that a portion
of the elongating stress imposed on the composite yarn is carried
by the stress-bearing member(s).
[0045] The Elastic Member The elastic member may be implemented
using one or a plurality (i.e., two or more) filaments of an
elastic yarn, such as that spandex material sold by DuPont Textiles
and Interiors (Wilmington, Del., USA, 19880) under the trademark
LYCRA.RTM..
[0046] The drafted length (N.times.L) of the elastic member is
defined to be that length to which the elastic member may be
stretched and return to within five percent (5%) of its relaxed
(stress free) unit length L. More generally, the draft N applied to
the elastic member is dependent upon the chemical and physical
properties of the polymer comprising the elastic member and the
covering and textile process used. In the covering process for
elastic members made from spandex yarns a draft of typically
between 1.0 and 8.0 and most preferably about 1.2 to about 5.0.
[0047] Alternatively, synthetic bicomponent multifilament textile
yarns may also be used to form the elastic member. The synthetic
bicomponent filament component polymers are thermoplastic, more
preferably the synthetic bicomponent filaments are melt spun, and
most preferably the component polymers are selected from the group
consisting of polyamides and polyesters.
[0048] A preferred class of polyamide bicomponent multifilament
textile yarns is those nylon bicomponent yarns which are
self-crimping, also called "self-texturing". These bicomponent
yarns comprise a component of nylon 66 polymer or copolyamide
having a first relative viscosity and a component of nylon 66
polymer or copolyamide having a second relative viscosity, wherein
both components of polymer or copolyamide are in a side-by-side
relationship as viewed in the cross section of the individual
filament. Self-crimping nylon yarn such as that yarn sold by DuPont
Textiles and Interiors under the trademark TACTEL.RTM. T-800.TM. is
an especially useful bicomponent elastic yarn.
[0049] The preferred polyester component polymers include
polyethylene terephthalate, polytrimethylene terephthalate and
polytetrabutylene terephthalate. The more preferred polyester
bicomponent filaments comprise a component of PET polymer and a
component of PTT polymer, both components of the filament are in a
side-by-side relationship as viewed in the cross section of the
individual filament. An especially advantageous filament yarn
meeting this description is that yarn sold by DuPont Textiles and
Interiors under the trademark T-400.TM. Next Generation Fiber. The
covering process for elastic members from these bicomponent yarns
involves the use of less draft than with spandex.
[0050] Typically, the draft for both polyamide or polyester
bicomponent multifilament textile yarns is between 1.0 and 5.0.
[0051] The conductive covering filament In its most basic form the
conductive covering filament comprises one or a plurality (i.e.,
two or more) strand(s) of metallic wire. These wire(s) may be
uninsulated or insulated with a suitable electrically nonconducting
polymer, e.g. nylon, polyurethane, polyester, polyethylene,
polytetrafluoroethylene and the like. Suitable insulated and
uninsulated wires (with diameter on the order of 0.02 mm to 0.35
mm) are available from; but not limited to: NV Bekaert SA,
Kortrijk, Belgium; Elektro-Feindraht AG, Escholzmatt, Switzerland
and New England Wire Technologies Corporation, Lisbon, N.H. The
metallic wire may be made of metal or metal alloys such as copper,
silver plated copper, aluminum, or stainless steel.
[0052] In an alternative form, the conductive covering filament
comprises a synthetic polymer yarn having one or more metallic
wire(s) thereon or an electrically conductive covering, coating or
polymer additive or sheath/core structure having a conductive core
portion. One such suitable yarn is X-static.RTM. available from
Laird Sauquoit Technologies, Inc. (300 Palm Street, Scranton, Pa.,
18505) under the trademark X-static.RTM. yarn. One suitable form of
X-static.RTM. yarn is based upon a 70 denier (77 dtex), 34 filament
textured nylon available from DuPont Textiles and Interiors,
Wilmington, Del. as product ID 70-XS-34.times.2 TEX 5Z
electroplated with electrically conductive silver. Another suitable
conductive yarn is a metal coated KEVLAR.RTM. yarn known as
ARACON.RTM. from E. I. DuPont de Nemours, Inc., Wilmington, Del.
Other conductive fibers which can serve as conductive covering
filaments, include polypyrrole and polyaniline coated filaments
which are known in the art; see for example: U.S. Pat. No.
6,360,315B1 to E. Smela. Combinations of conductive covering yarn
forms are useful depending upon the application and are within the
scope of the invention.
[0053] Suitable synthetic polymer nonconducting yarns are selected
from among continuous filament nylon yarns (e.g. from synthetic
nylon polymers commonly designated as N66, N6, N610, N612, N7, N9),
continuous filament polyester yarns (e.g. from synthetic polyester
polymers commonly designated as PET, 3GT, 4GT, 2GN, 3GN, 4GN),
staple nylon yarns, or staple polyester yarns. Such composite
conductive yarn may be formed by conventional yarn spinning
techniques to produce composite yarns, such as plied, spun or
textured yarns.
[0054] Whatever form chosen the length of the conducting conductive
covering filament surrounding the elastic member is determined
according to the elastic limit of the elastic member. Thus, the
conductive covering filament surrounding a relaxed unit length L of
the elastic member has a total unit length given by A(N.times.L),
where A is some real number greater than one (1) and N is a number
in the range of about 1.0 to about 8.0. Thus the conductive
covering filament has a length that is greater than the drafted
length of the elastic member.
[0055] The alternative form of the conductive covering filament may
be made by surrounding the synthetic polymer yarn with multiple
turns of a metallic wire.
[0056] Optional stress-bearing member The optional stress-bearing
member of the electrically conductive elastic composite yarn of the
present invention may be made from nonconducting inelastic
synthetic polymer fiber(s) or from natural textile fibers like
cotton, wool, silk and linen. These synthetic polymer fibers may be
continuous filament or staple yarns selected from multifilament
flat yarns, partially oriented yarns, textured yarns, bicomponent
yarns selected from nylon, polyester or filament yarn blends.
[0057] If utilized, the stress-bearing member surrounding the
elastic member is chosen to have a total unit length of
B(N.times.L), where B is some real number greater than one (1). The
choice of the numbers A and B determines the relative lengths of
the conductive covering filament and any stress-bearing member.
Where A>B, for example, it is ensured that the conducting
covering filament is not stressed or significantly extended near
its breaking elongation. Furthermore, such a choice of A and B
ensures that the stress-bearing member becomes the strength member
of the composite yarn and will carry substantially all the
elongating stress of the extension load at the elastic limit of the
elastic member. Thus, the stress-bearing member has a total length
less than the length of the conductive covering filament such that
a portion of the elongating stress imposed on the composite yarn is
carried by the stress-bearing member. The length of the
stress-bearing member should be greater than, or equal to, the
drafted length (N.times.L) of the elastic member.
[0058] The stress-bearing member is preferably nylon. Nylon yarns
comprised of synthetic polyamide component polymers such as nylon
6, nylon 66, nylon 46, nylon 7, nylon 9, nylon 10, nylon 11, nylon
610, nylon 612, nylon 12 and mixtures and copolyamides thereof are
preferred. In the case of copolyamides, especially preferred are
those including nylon 66 with up to 40 mole percent of a
polyadipamide wherein the aliphatic diamine component is selected
from the group of diamines available from E. I. Du Pont de Nemours
and Company, Inc. (Wilmington, Del., USA, 19880) under the
respective trademarks DYTEK A.RTM. and DYTEK EP.RTM.
[0059] Making the stress-bearing member from nylon renders the
composite yarn dyeable using conventional dyes and processes for
coloration of textile nylon yarns and traditional nylon covered
spandex yarns.
[0060] If the stress-bearing member is polyester the preferred
polyester is either polyethylene terephthalate (2GT, a.k.a. PET),
polytrimethylene terephthalate (3GT, a.k.a. PTT) or
polytetrabutylene terephthalate (4GT). Making the stress-bearing
member from polyester multifilament yarns also permits ease of
dyeing and handling in traditional textile processes.
[0061] The conductive covering filament and the optional
stress-bearing member surround the elastic member in a
substantially helical fashion along the axis thereof.
[0062] The relative amounts of the conductive covering filament and
the stress-bearing member (if used) are selected according to
ability of the elastic member to extend and return substantially to
its unstretched length (that is, undeformed by the extension) and
on the electrical properties of the conductive covering filament.
As used herein "undeformed" means that the elastic member returns
to within about +/-five percent (5%) of its relaxed (stress free)
unit length L.
[0063] It has been found that any of the traditional textile
process for single covering, double covering, air jet covering,
entangling, twisting or wrapping of elastic filaments with
conductive filament and the optional stress-bearing member yarns is
suitable for making the electrically conducting elastic composite
yarn according to the invention.
[0064] In most cases, the order in which the elastic member is
surrounded by the conductive covering filament and the optional
stress-bearing member is immaterial for obtaining an elastic
composite yarn. A desirable characteristic of these electrically
conducting elastic composite yarns of this construction is their
stress-strain behavior. For example, under the stress of an
elongating applied force the conductive covering filament of the
composite yarn, disposed about the elastic member in multiple wraps
[typically from one turn (a single wrap) to about 10,000 turns], is
free to extend without strain due to the external stress.
[0065] Similarly, the stress-bearing member, when also disposed
about the elastic member in multiple wraps, again, typically from
one turn (a single wrap) to about 10,000 turns, is free to extend.
If the composite yarn is stretched near to the break extension of
the elastic member, the stress-bearing member is available to take
a portion of the load and effectively preserve the elastic member
and the conductive covering filament from breaking. The term
"portion of the load" is used herein to mean any amount from 1 to
99 percent of the load, and more preferably 10% to 80% of the load;
and most preferably 25% to 50% of the load.
[0066] The elastic member may optionally be sinuously wrapped by
the conductive covering filament and the optional stress-bearing
member. Sinuous wrapping is schematically represented in FIG. 14,
where an elastic member (40), e.g. a LYCRA.RTM. yarn, is wrapped
with a conductive covering filament (10), e.g. a metallic wire, in
such a way that the wraps are characterized by a sinuous period
(P).
[0067] Specific embodiments and procedures of the present invention
will now be described further, by way of example, as follows.
Test Methods
[0068] Measurement of Fiber and Yarn Stress-Strain Properties Fiber
and Yarn Stress-Strain Properties were determined using a
dynamometer at a constant rate of extension to the point of
rupture. The dynamometer used was that manufactured by Instron
Corp, 100 Royall Street, Canton, Massachusetts, 02021 USA.
[0069] The specimens were conditioned to 22.degree. C..+-.1.degree.
C. and 60%.+-.5% R.H. The test was performed at a gauge length of 5
cm and crosshead speed of 50 cm/min. For metal wires and bare
elastic yarns, threads measuring about 20 cm were removed from the
bobbin and let relax on a velvet board for at least 16 hours in
air-conditioned laboratory. A specimen of this yarn was placed in
the jaws with a pre-tension weight corresponding to the yarn dtex
so as not to give either tension or slack.
[0070] For the conductive composite yarns of the invention, test
specimens were prepared under two different methods as follows:
[0071] (Method 1) Specimen prepared as in the case of bare fibers
(relaxed state)
[0072] (Method 2) Specimen prepared by taking the yarn directly
from the bobbin.
[0073] The results obtained from the two methods enable direct
comparison between the electrically conductive elastic composite
yarn and its components (Method 1), as well as, assuring intact
positioning of the electrically conductive elastic composite yarn
during the measurement (variation between Methods 1 & 2). In
addition tests were performed under varied pretension load that
sets the yarn relaxed length. In this case the range of pretension
loads applied simulates: (i) the pretension appropriate for the
elastic component of the electrically conductive elastic composite
yarn so as not to give either tension or slack; these results can
then be in direct comparison with the results obtained from the
individual components of the electrically conductive elastic
composite yarn, and (ii) the tension load applied on the yarn
during knitting or weaving processes; these results are then a
representation of the processability of the yarn as well as the
influence of the conductive composite yarn on the elastic
performance of the knitted or woven fabric based on this yarn. It
is expected that the pretension load influences available
elongation of the yarn (at a higher pretension load a lower
available elongation is measured) but not the ultimate strength of
the yarn.
[0074] Measurement of Fabric Stretch Fabric stretch and recovery
for a stretch woven fabric is determined using a universal
electromechanical test and data acquisition system to perform a
constant rate of extension tensile test. A suitable
electromechanical test and data acquisition system is available
from Instron Corp, 100 Royall Street, Canton, Massachusetts, 02021
USA.
[0075] Two fabric properties are measured using this instrument:
fabric stretch and the fabric growth (deformation). The available
fabric stretch is the amount of elongation caused by a specific
load between 0 and 30 Newtons and expressed as a percentage change
in length of the original fabric specimen as it is stretched at a
rate of 300 mm per minute. The fabric growth is the unrecovered
length of a fabric specimen which has been held at 80% of available
fabric stretch for 30 minutes then allowed to relax for 60 minutes.
Where 80% of available fabric stretch is greater than 35% of the
fabric elongation, this test is limited to 35% elongation. The
fabric growth is then expressed as a percentage of the original
length.
[0076] The elongation or maximum stretch of stretch woven fabrics
in the stretch direction is determined using a three-cycle test
procedure. The maximum elongation measured is the ratio of the
maximum extension of the test specimen to the initial sample length
found in the third test cycle at load of 30 Newtons. This third
cycle value corresponds to hand elongation of the fabric specimen.
This test was performed using the above-referenced universal
electromechanical test and data acquisition system specifically
equipped for this three-cycle test.
EXAMPLES
[0077] Parenthetical reference numerals present in the discussion
of the Examples refer to the reference characters used in the
appropriate drawing (s).
[0078] Comparative Example Electrically conducting wires having an
electrically insulated polymer outer coating were examined for
their stress and strain properties using the dynamometer and Method
1 for measuring individual components of the electrically
conductive elastic composite yarn. Samples of three wires available
from ELEKTRO-FEINDRAHT AG, Switzerland, were tested. The metallic
portion of the wires is shown in FIGS. 1A and 1B. The first sample
wire had a nominal diameter of 20 micrometers (.mu.m), a second
sample 30 .mu.m, and a third sample 40 .mu.m. The stress-strain
curves of these three samples are shown in FIG. 2; using Test
Method 1. These curves are typical of fine metallic wires. These
wires exhibit a quite high modulus which along with the force to
break increases with an increase in the wire diameter. All the
wires break before elongation to 20% of their test specimen length,
characterized by a quite low ultimate strength. Clearly, where
metallic wires are used in textile fabrics and apparel there is a
severe limit to the elongation available. Such wires in garments
subject to stretch from movement of the wearer would be
undependable conductors of electricity due to breakage of the
wire.
Example 1 of the Invention
FIGS. 3a, 3b, 4, 5
[0079] A 44 decitex (dtex) elastic core (40) made of LYCRA.RTM.
spandex yarn was wrapped with a 20 .mu.m diameter insulated
silver-copper metal wire (10) obtained from ELEKTRO-FEINDRAHT AG,
Switzerland using a standard spandex covering process. Covering was
done on an I.C.B.T. machine model G307. During this process
LYCRA.RTM. spandex yarn was drafted to a value of 3.2 times (i.e.
N=3.2) and was wrapped with two metal wires (10) of the same type,
one twisted to the "S" and the other to the "Z" direction, to
produce a electrically conductive elastic composite yarn (50). The
wires (10) were wrapped at 1700 turns/meter (turns of wire per
meter of drafted Lycra.RTM. spandex yarn) (5440 turns for each
relaxed unit length L) for the first covering and at 1450
turns/meter (4640 turns for each relaxed unit length L) for the
second covering. An SEM picture of this composite yarn is shown in
the relaxed (FIG. 3a) and stretched states (FIG. 3b). The
stress-strain curve shown in FIG. 4 is for electrically conductive
elastic composite yarn (50) measured as in the comparative example
using Test Method 1 with an applied pretension load of 100 mg. This
electrically conductive elastic composite yarn (50) exhibits an
exceptional stretch behavior to over 50% more than the test
specimen length and elongates to the range of 80% before it breaks
exhibiting a higher ultimate strength than the 20 .mu.m wire
individually. This process allows production of an electrically
conductive elastic composite yarn (50) that exhibits an elongation
to break in the range of 80% and a force to break in the range of
30 cN, compared to the individual metal wire that exhibits an
elongation to break of only 7% and a force to break of only 8 cN.
The stress-strain curve of this electrically conductive elastic
composite yarn (50) was also measured according to Test Method 2
using a higher pretension load of 1 gram. This pretension more
closely corresponds to that tension applied during a knitting
process (FIG. 5). Under these conditions the elongation to break of
the electrically conductive elastic composite yarn (50) is in the
range of 35%. This elongation indicates that yarn (50) is easier
handle in a textile process and will provide a stretch fabric
compared to the individual metal wire yarn. As can be seen from the
characteristic stress-strain curve of this example, the break of
the electrically conductive elastic composite yarn (50) is caused
by the metal wire breaking before the elastic member of the
composite yarn (50) breaks.
Example 2 of the Invention
FIGS. 3c, 3d, 6
[0080] An electrically conducting elastic composite yarn (60)
according to the invention was produced under the same conditions
as in Example 1 except that the metal wires (10) were wrapped at
2200 turns/meter (7040 turns for each relaxed unit length L) and at
1870 turns/meter (5984 turns for each relaxed unit length L) for
the first and second coverings, respectively. An SEM picture of
this electrically conductive elastic composite yarn (60) is shown
in FIG. 3c (relaxed state) and FIG. 3d (stretched state). These
Figures clearly show a higher covering of the elastic member (40)
by the metal wires (10) in comparison with Example 1. The
stress-strain curve of this electrically conductive elastic
composite yarn (60) is shown in FIG. 6; measured as in the
Comparative Example using Test Method 1 and an applied pretension
load of 100 mg. This electrically conductive elastic composite yarn
(60) exhibits a similar ultimate strength but lower available
elongation compared to the electrically conductive elastic
composite yarn of Example 1. This process allows production of an
electrically conducting composite yarn exhibiting an elongation to
break in the range of 40% and a force to break in the range of 30
cN, compared to the individual metal wires (10) that exhibit an
elongation to break of only 7% and a force to break of only 8 cN.
The same electrically conducting composite yarn tested under Method
2, but using a pretension load of 1 gram, showed a similar behavior
to the electrically conducting composite yarn of Example 1 under
the same test method indicating good handling during a textile
process.
[0081] The results shown by Examples 1 and 2 of the invention
indicate that electrically conductive elastic composite yarns can
be produced by the double covering process at varying covering
fractions of the elastic member which have exceptional stretch
performance and higher strength compared to the individual metal
wire.
[0082] This flexibility in construction of electrically conductive
elastic composite yarn of the invention is both interesting and
desirable for applications utilizing the electrical properties of
such electrically conductive elastic composite yarns. For example,
in wearable electronics, a magnetic field may be modulated or
suppressed depending on the requirements of the application by
varying the construction of the electrically conductive elastic
composite yarn.
Example 3 of the Invention
FIGS. 7a, 7b, 8
[0083] A 44 decitex (dtex) elastic core (40) made of LYCRA.RTM.
spandex yarn as used in the Examples 1 and 2 of the invention was
covered with a 20 .mu.m nominal diameter insulated silver-copper
metal wire (10) obtained from ELEKTRO-FEINDRAHT AG, Switzerland,
and a with a 22 dtex 7 filament stress-bearing yarn of TACTEL.RTM.
nylon (42) using the same covering process as in Example 1 of the
invention. During this process the elastic member was drafted to a
draft of 3.2 times and covered with 2200 turns/meter (7040 turns
for each relaxed unit length L) of wire (10) per meter and 1870
turns/meter (5984 turns for each relaxed unit length L) of
TACTEL.RTM. nylon (42). An SEM picture of this electrically
conducting elastic composite yarn (70) is shown in the relaxed
state (FIG. 7a) and stretched state (FIG. 7b). It is evident from
this picture that such process provides a higher protection for the
conductive covering filament (10) compared to Examples 1 and 2 of
the invention.
[0084] This feature is desirable in applications where an
insulation layer is sought for a metal wire or to provide
protection of the wire (10) during textile processing. The
incorporation of stress-bearing nylon yarn (42) also determines
certain aesthetics. Hand and texture of the electrically conducting
composite yarn (70) are determined primarily by the stress-bearing
nylon yarn (42) comprising the outer layer of the electrically
conductive elastic composite yarn (70). This is desirable for the
overall aesthetics and touch of the garment. The stress-strain
curve of electrically conducting composite yarn (70) shown in FIG.
8 is measured as in the Comparative Example using Test Method 1
with an applied pretension load of 100 mg. This electrically
conducting elastic composite yarn (70) elongates easily to over 80%
using less force to elongate than the breaking stress of the 20
.mu.m wire individually. This electrically conducting elastic
composite yarn (70) exhibits an elongation to break in the range of
120% and an ultimate strength in the range of 120 cN which is
significantly higher than the available elongation and strength of
any metal wire sample tested in the Comparative Example. Tested
under Method 2 and a pretension load of 1 gram, this yarn (70)
shows a soft stretch in the range of 0-35% elongation, which
indicates significant contribution of this yarn in the elastic
performance of a garment made of this yarn. Incorporation of
stress-bearing nylon yarn (42) in the electrically conducting
elastic composite yarn (70) results in a significant increase of
the ultimate strength as well as elongation of the electrically
conducting composite yarn.
Example 4 of the Invention
FIGS. 7c, 7d, 9
[0085] An electrically conducting elastic composite yarn (80) was
produced under the same conditions of Example 3 of the invention,
except for the following: the stress-bearing Tactel.RTM. nylon yarn
(44) was a 44 dtex 34 filament microfiber. The first covering was
1500 turns/meter (4800 turns for each relaxed unit length L) of
wire (10) and the second covering was 1280 turns/meter (4096 turns
for each relaxed unit length L) of nylon fiber (44) of drafted
elastic core (40). An SEM picture of this electrically conducting
elastic composite yarn (80) is shown in the relaxed state (FIG. 7c)
and stretched state (FIG. 7c). The bulkiness of this electrically
conducting elastic composite yarn (80) provides for good protection
of the metal wire (10) while taking on the soft aesthetics of a
microfiber stress-bearing yarn (44). The stress-strain curve of
this yarn (80) is shown in FIG. 9 as measured in the Comparative
Example using Test Method 1 with an applied pretension load of 100
mg. This electrically conducting elastic composite yarn (80)
elongates easily to over 80% using less force to elongate than the
breaking stress of the 20 .mu.m wire individually, and exhibits an
elongation to break in the range of 120% and an ultimate strength
in the range of 200 cN which is significantly higher than the
available elongation and strength of any metal wire sample tested
in the Comparative Example. Tested under Method 2 and a pretension
load of 1 gram, electrically conducting elastic composite yarn (80)
is shows a soft stretch in the range of zero to 35% elongation.
Such a result is indicative of the significant contribution in the
elastic performance of a garment made from the yarn (80).
Incorporation of a stronger stress-bearing nylon fiber (44) in the
electrically conductive elastic composite yarn (80) compared with
Example 3 of the invention results in a further enhancement of the
ultimate strength of the electrically conductive elastic composite
yarn (80).
Example 5 of the Invention
FIGS. 10a, 10b, 11
[0086] A 44 decitex (dtex) elastic member (40) made of LYCRA.RTM.
spandex yarn was covered with a stress-bearing 44 dtex 34 filament
TACTEL.RTM. Nylon microfiber (46) and metal wire (10) via a
standard air-jet covering process. This covering was made on an SSM
(Scharer Schweiter Mettler AG) 10-position machine model DP2-CIS.
An SEM picture of this electrically conducting composite yarn (90)
is shown in the relaxed state (FIG. 10a) and stretched state (FIG.
10b). During this process the metallic wire (10) forms loops due to
its monofilament nature. However in the stretched state the
metallic wires (10) are completely protected by the stress-bearing
nylon fiber (46). The structure provided by the air-jet covering
process is not well-defined nor in a predetermined geometrical
direction as in the simple covering processes of Examples 1-4 of
this invention. The stress-strain curve of this yarn (90) is shown
in FIG. 11 measured as in the Comparative Example using Test Method
1 with an applied pretension load of 100 mg. This electrically
conductive elastic composite yarn (90) elongates easily to over
200% using less force to elongate than the breaking stress of the
20 .mu.m wire individually, and exhibits an elongation to break in
the range of 280% and an ultimate strength in the range of 200 cN.
This elongation is significantly higher than the available
elongation and strength of any metal wire sample tested in the
Comparative Example. Tested under Method 2 and a pretension load of
1 gram, electrically conductive elastic composite yarn (90) shows a
soft stretch in the range of 100% elongation. This indicates that a
significant contribution in the elastic performance of a garment of
the yarn (90) is expected. Incorporation of a stress-bearing nylon
fiber (46) in the electrically conductive elastic composite yarn
(90), via air-jet covering, results in a significant enhancement of
the ultimate strength of the composite yarn (90) which is similar
with the observations made on electrically conductive elastic
composite yarn by the double-covering process (e.g. Examples 3 and
4 of the invention). Further, it is observed that the air-jet
covering process allows for a still higher available elongation
range when compared to the processes using the same draft of the
LYCRA.RTM. elastic member (40) in Examples 3 and 4. This feature
increases the range of possible elastic performance in garments
made from such electrically conducting elastic composite yarn.
Example 6 of the Invention
FIGS. 12a, 12b
[0087] A fabric (100) was produced using electrically conductive
elastic composite yarn (70) described in Invention Example 3. The
fabric (100) was in the form of a knitted tube made on a Lonati 500
hosiery machine. This knitting process permits examination of the
knittability of the yarn (70) under critical knitting conditions.
This electrically conductive elastic composite yarn (70) yarn
processed very well with no breaks providing a uniform knitted
fabric (100). An SEM picture of this fabric (100) is given in FIG.
12a in a relaxed state and in FIG. 12b in stretched state.
Example 7 of the Invention
FIGS. 13a, 13b
[0088] A fabric (110) was produced using the electrically
conductive elastic composite yarn (80) described in Invention
Example 4 of the invention. The fabric (110) again made in a Lonati
500 hosiery machine as in Example 6. The electrically conductive
elastic composite yarn (80) processed very well with no breaks
providing a uniform knitted fabric. An SEM picture of this fabric
(110) is given in FIG. 13a in the relaxed state and in FIG. 13b in
stretched state.
[0089] The examples are for the purpose of illustration only. Many
other embodiments falling within the scope of the accompanying
claims will be apparent to the skilled person.
* * * * *